Field of the Invention
The present invention relates to a brake pedal simulator for a vehicle, and more particularly, to a brake pedal simulator for a vehicle for implementing a change in a foot effort of a brake pedal according to a change in a stroke.
Description of Related Art
In general, a brake pedal unit of a vehicle includes a pedal mounting bracket installed inside a vehicle cabin between a dash panel and a cowl panel, an operation lever hinge-connected to one side of the pedal mounting bracket, and a pedal under the operation lever.
A spring is installed between the pedal mounting bracket and the operation lever for restoration of the operation lever.
The operation lever is connected with a push rod of a brake booster at one side to provide the brake booster with operation force.
Accordingly, when a driver steps on the pedal, a foot effort applied to the pedal is amplified by the brake booster to operate a master cylinder, and the master cylinder generates hydraulic pressure and provides each wheel cylinder with the generated hydraulic pressure to generate braking force.
A brake pedal simulator for reproducing an operation of the brake pedal unit is configured and tested before applying the brake pedal unit to an actual vehicle.
In a case of an electric brake, a method of operating the brake pedal simulator includes a method of transmitting the amount of flow inside one cylinder to the other cylinder so as to implement the same sensitivity of a pedal feel as that of a hydraulic brake and a method of using two or more springs or an elastic member, such as rubber, inside the cylinder.
FIG. 8 is a graph illustrating a relation between a stroke and a foot effort of a brake pedal of an actual vehicle.
As illustrated in FIG. 8, it can be seen that reaction force for the stroke of the brake pedal of the actual vehicle gradually increases with a small inclination at a section in which the stroke is small, and then an inclination of reaction force of the stroke for the foot effort increases according to the increase of the stroke.
However, in a general brake pedal simulator for a vehicle, when a foot effort is generated by using the springs inside the master cylinder, a spring constant is fixed. Accordingly, when a foot effort inclination is changed from a section in which an initial effort inclination is small to a section in which a foot effort inclination after the middle is high, there is a problem in that a sense of difference (feeling that the foot effort suddenly becomes heavy) is generated. That is, a section in which the reaction force for the brake pedal sharply increases is generated.
Further, when rubber is used, there is a problem in that hardness of rubber is changed according to a change in a temperature and thus a foot effort is also changed.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.